Solenoid valve

ABSTRACT

A solenoid valve which includes a magnetic nucleus, a movable valve element of material sensible to a magnetic field, and an electric circuitry which creates a circulating magnetic flux which involves said magnetic nucleus and said movable element, so that the movable element is internally guided.

United States Patent Inventor Appl. No.

Filed Patented Assignee Priority Aldo Bassi Milan, Italy 773,581

Nov. 5, 1968 Jan. 5, 1971 Alfa Romeo S. p. A. Milan, Italy a company ofItaly Dec. 21, 19 67 Italy SOLENOID VALVE 5 Claims, 3 Drawing Figs.

US. Cl.....

Int.Cl Fl6k3l/06 frimary Examiner-Arnold Rosenthal Attorney-Holman &Stern ABSTRACT: A solenoid valve which includes a magnetic nucleus, amovable valve element of material sensible to a magnetic field, and anelectric circuitry which creates a circulating magnetic flux whichinvolves said magnetic nucleus and said movable element, so that themovable element is internally guided.

SOLENOID VALVE BACKGROUND OF THE INVENTION This invention relates to asolenoid valve particularly suitable for constituting the actuator of acontrol system for intermittent flows of fluid.

Numerous types of solenoid valves are known for inserting into fluidpipes which are openable at predetermined time intervals at which fluiddischarges take place, the extent of which varies as a function 'ofduration of-opening of the solenoid valve, with the duration of theopening being related to the duration of an electrical control signal.

Obviously the shorter the response times on the solenoid valve withrespect to the signal, the finer is the control. It is hence important,in a system for controlling the flow of a fluid, to use a solenoid valvehaving a small response time, which is a characteristic which dependsessentiallyon the weight and dimensions of the movable element includedin the solenoid valve. In addition, its hydraulic permeability must belarge in order to give a ready passage for the quantity of fluidrequired.

In the solenoid valves at present available, the movable element slidesinside a hollow magnetic nucleus and is guided externally by the lateralwalls of this cavity, which forms the duct for the fluid. Normally themovable element consists of a hollow metallic cylinder containinginserted elements of suitable material at the two ends. One element isin the form of a cone and is inserted into and withdrawn from acontraction in the fluid duct in order respectively to impede and permitthe passage of the fluid according to whether the electrical windingsarranged around the magneticnucleus are fed or not fed. In said cone orclose thereto there are lateral oblique holes which permit the passageof the fluid into a chamber which is placed into communication with saidcontraction by the withdrawal of the cone from the contraction itself.The other element is placed between the metallic part of the movableelement and the magnetic nucleus and has the function of impedingmagnetic short circuiting.

The principle disadvantages of thes'esolenoid valves derive from thefact that the guide of themovable element is external to the elementitself. This hinders the reduction of the dimensions of the movableelement below a certain limit, because of which the response time of thesolenoid valve cannot be as short as would be desired. In addition, thelarge dimensions of the movable element give rise to large externaldimensions and hence encumbrance of the solenoid valve, which makes theinsertion of the solenoid valve into the most suitable position for itsutilization difficult. Any considerable limiting of the dimensions ofthe movable element is also hindered by the presence of the element inthe form of a cone, which being fixed to the hollow cylinder, requires acylinder of certain dimensions in order to obtain a good reciprocalfixing.

SUMMARY OF THE INVENTION The above-mentioned mentioned disadvantages areovercome by the solenoid valve accordingto-the invention, which includesa magnetic nucleus containing an elongated cavity open at one end andterminating at the other end in a widened closed chamber, and into whichis inserted a projection contained by said closed extremity, saidprojection being substantially aligned with said cavity and throughwhich is a hole substantially coaxial with said cavity, this holecontinuing through said closed extremity so as to finish on the outsideof the magnetic nucleus, an element which moves between two extremepositions being guided by said projection so that it slides, saidmovable element consisting of a tubular part of material sensible to amagnet field and of a cover in a material which forms a closing gasketfor said tubular part, said cover closing the holethrough saidprojection when the movable element is in a first extreme position andimpeding contact between said tubular part of the movable element andthe magnetic nucleus when the movable element is in the second extremeposition, resilient means being provided which thrust said movableelement into said first extreme position, said tubular part of themovable element containing lateral holes close to said cover which putthe hole through said projection into communication with said chamberwhen the movable element is in said second extreme position, saidmagnetic nucleus containing lateral holes which put said elongatedcavity into communication with said chamber for any position of themovable element, an electric winding being arranged on said magneticnucleus which creates, if fed, a circulation'of magnetic flux in amagnetic circuit which includes said magnetic nucleus and said movableelement.

give larger dimensions to the narrowest sections traversed by themagnetic flux, with the position of these sections corresponding to themovable element. The improvements in the hydraulic permeability derivefrom the fact that is it is possible to give larger dimensions to thelateral holes of the movable element even though the dimensions of themovable element itself are reduced.

Other advantages are related to said cover of gasket material whichcloses the tubular part of the movable element and which serves both asan element to intercept the hydraulic flow (it is in fact such as toclose the hole through the said projection and hence close the solenoidvalve when the movable element is in its first extreme position) and forseparating the tubular part of the tubular element from the magneticnucleus (when the movable element is in the other of its extremepositions) so as to impede a magnetic short circuit which would provokehysteresis and late responses due to an excess of magnetic flux. Thesame cover carries out both functions, while in the past two distinctgasket elements were needed.

In total, a lesser time of response. of the solenoid valve to the signalfor delivering a certain flow is obtained, with a smaller winding and alesser absorption of current, that is, a greater facility in realizingthe electrical or electronic signal control device. All this leads toobvious advantages of lightness of weight and also of simple andeconomic manufacture.

BRIEF DESCRIPTION OF THE DRAWINGS DETAILED DESCRIPTION OF THE INVENTIONReferring particularly to FIG. 1, the solenoid valve includes a magneticnucleus consisting of two elements arranged one inside the other. Anexternal element 1 consists of an elongated block containing an intemalcavity open at one end and in which is inserted an internal element 8which consists of an elongated block through which there is a hole 14.

The internal element 8 is partially inserted in the cavity of theexternal element so that between the internal element and the closedextremity of the external element there is a widened chamber 10. Theclosed extremity of the external element contains a cylindrical axialprojection 2 pointing towards the inside of the solenoid valve andthrough which there is an axial hole 3 which continues through saidclosed extremity of the element 1 before enlarging itself into a hole 13which emerges on the outside of the solenoid valve. The cylindricalprojection 2 acts as a guide for a movable element in the form of anoverturned bowl consisting of a tubular metallic part 4 and a cover 6 ofplastic material which closes said tubular part 4. The movable element 5can oscillate between two extreme positions. In a first extreme position(that of FIG. 1) the cover 6 rests on the extremity of the projection 2so as to close the hole 3. 1n the second extreme position, the cover 6rests on the internal extremity of the element 8 so as to impede anycontact between the part of the movable element 5 and the internalelement 8 of the magnetic nucleus.

The movable element 5 further contains some lateral holes 11 (FIG. 2)arranged so as to put the internal cavity of said tubular part and hencethe hole 3 in communication with the chamber when the movable element isin said second extreme position and so as to be closed by the saidprojection 2 when the movable element is in said first extreme position(FIG. 1).

The lower extremity of the internal element- 8 contains lateral holes 9,with said holes permitting communication with said holes permittingcommunication between the hole 14 and the chamber 10 when themovableelement is in said second extreme position and so as to be closedby the said projection 2 when the movable element is in-said secondextreme position.

The movable element is thrust into the position of FIG. 1 by a spring '7arranged between the cap 6 of the movable element and a block 15 theposition of which in the chamber 14 is adjusted by a nut 17 and alocking nut 16 which screw into the said cavity 14.

The movement of the movable element from the position of FIG. 1 iscontrolled by sending an electrical impulse to electrical windings 12arranged between the external walls of the internal element 8 and theinternal wall of the external element 1. Under these conditions there isa passage of magnetic flux in the circuit including the external element1, the metallic part of the movable element 5 and the internal element8.

This magnetic flux provokes the raising of the movable element until itcarries the cover 6 into contact with the lower extremity of theinternal element 8. As the holes 11 and the hole 13 are open and as thesolenoid valve is inserted in a fluid carrying pipe, there is a passageof fluid from the entry port 14 to the exit port 13 through the holes 9of the internal element 8, the chamber 10,the holes 11 of the movableelement and the hole 3 of the projection 2. The presence of the cover 6of plastic material impedes the contact between the metallic part of themovable element 5 and the magnet nucleus, thus avoiding magnetic shortcircuiting.

When the impulse to the inlet terminals of the windings 12 ceases, thespring 7 thrusts the movable element back into the position of FIG. 1.The holes 11 of the movable element and the hole 3 of the projection 2are closed and the passage of I claim: 1. A solenoid valve whichincludes a magnetic nucleus containing an elongated cavity open at oneend and terminating at the other end in a widened closed chamber, inwhich is inserted a projection contained by said closed extremity, saidprojection being substantially aligned with said cavity and throughwhich there is a hole substantially coaxial with said cavity, this holecontinuing through said closed extremity so as to emerge on the outsideof the magnetic nucleus, a movable element being guided by saidprojection so that it slides between two extreme positions, said movableelement consisting of a tubular part of a material, sensitive to amagnetic field and of a cover of gasket material for closing saidtubular part, said cover closing the hole through thesaid projectionwhen the movable element is in a first extreme position and impedingcontact between said tubular part of the movable element and themagnetic nucleus when the movable element is in the second extremeposition, resilient means fo r thrust ing said movable element mto saidfirst extreme position being provided, said tubular part of the movableelement containing lateral holes close to said cover which out the holethrough said projection into communication with said chamber when themovable element is in said second extreme position, said magneticnucleus containing passages which put said elongated cavity intocommunication with said chamber at any position of the movable element,electrical windings being arranged on said magnetic nucleus whichcreate, if fed, a circulation of magnetic flux in a magnetic circuitincluding said magnetic nucleus and said movable element.

2, The solenoid valve as claimed in claim 1, in which said magneticnucleus consists of an external elongated element containing a cavityopen at one end, said projection projecting from said external elementat the closed end, and of an internal elongated element through whichthere is a hole substantially coaxial with the cavity of said externalelement, said internal element being partially inserted into saidexternal element so that between said elementsis formed said widenedchamber, said windings being arranged between the external wall of theinternal element and the internal wall of the external element.

3. The solenoid valve asclaimed in claim I in which said projection isof cylindrical development. j

4. The solenoid valve as claimed in claim 1, in which said movableelement is in the form of a bowl whose bottom consists of said cover.

5. The solenoid valve as claimed in claim 4, in which said cover is ofplastic material.

1. A solenoid valve which includes a magnetic nucleus containing anelongated cavity open at one end and terminating at the other end in awidened closed chamber, in which is inserted a projection contained bysaid closed extremity, said projection being substantially aligned withsaid cavity and through which there is a hole substantially coaxial withsaid cavity, this hole continuing through said closed extremity so as toemerge on the outside of the magnetic nucleus, a movable element beingguided by said projection so that it slides between two extremepositions, said movable element consisting of a tubular part of amaterial, sensitive to a magnetic field and of a cover of gasketmaterial for closing said tubular part, said cover closing the holethrough the said projection when the movable element is in a firstextreme position and impeding contact between said tubular part of themovable element and the magnetic nucleus when the movable element is inthe second extreme position, resilient means for thrusting said movableelement into said first extreme position being provided, said tubularpart of the movable element containing lateral holes close to said coverwhich out the hole through said projection into communication with saidchamber when the movable element is in said second extreme position,said magnetic nucleus containing passages which put said elongatedcavity into communication with said chamber at any position of themovable element, electrical windings being arranged on said magneticnucleus which create, if fed, a circulation of magnetic flux in amagnetic circuit including said magnetic nucleus and said movableelement.
 2. The solenoid valve as claimed in claim 1, in which saidmagnetic nucleus consists of an external elongated element containing acavity open at one end, said projection projecting from said externalelement at the closed end, and of an internal elongated element throughwhich there is a hole substantially coaxial with the cavity of saidexternal element, said internal element being partially inserted intosaid external element so that between said elements is formed saidwidened chamber, said windings being arranged between the external wallof the internal element and the internal wall of the external element.3. The solenoid valve as claimed in claim 1 in which said projection isof cylindrical development.
 4. The solenoid valve as claimed in claim 1,in which said movable element is in the form of a bowl whose bottomconsists of said cover.
 5. The solenoid valve as claimed in claim 4, inwhich said cover is of plastic material.